The venue of the seminar: The University of Queensland, Room 78-622, St Lucia Campus, Brisbane

Title: Continuous Queries and Reactive Behavior Management in Moving Object
Databases
Speaker: Prof. Peter Scheuermann (Northwestern University, USA)

Abstract:
Unlike traditional applications where queries are instantaneous, many queries
of interest in moving object databases (MOD) are continuous in nature and
require constant re-evaluation over the history of the objects. We assume that
that the motion of objects is represented by trajectories, which consists of a
sequence of 3D points. We present first a comprehensive set of techniques, both
static and dynamic, for minimizing the costs involved in reevaluating
continuous queries in response to bulk updates. The static techniques
correspond to specifying the values of various semantic dimensions of trigger
execution. The dynamic techniques include an in-memory shared reevaluation
algorithm, adapting  query indexing techniques to trajectory data, and
utilizing ordering based on space-filling curves to improve the I/O efficiency.

We next address the problem of handling event notification in MOD, by
introducing a class of dynamic topological predicates, such moving along and
moving towards. We show that traditional triggers are inadequate for handling
the reactive behavior of these topological predicates since they repeatedly
evaluate the conditions on the entire past trajectory. Motivated by this we
introduce a new paradigm for expressing reactive behavior in distributed
environments in which data continuously changes over time and which allows
users to explicitly specify how the triggers should be (self) modified. We call
this paradigm Evolving and Context-Aware Event Condition Action (ECA) 2. Our
model combines reactive behavior with proactive impact by modifying dynamically
the event/conditions and actions monitored. Since both the monitored event and
the condition part of the trigger can be continuous in nature, we introduce the
concept of metatriggers to coordinate the detection of events and the
evaluation of conditions.

Biography:
Professor Peter Scheuermann is a Professor of Electrical Engineering and
Computer Science at Northwestern University. He has held visiting professor
positions with the Free University of Amsterdam, the University of Hamburg, the
Technical University of Berlin and the Swiss Federal Institute of Technology,
Zurich. During 1997-1998 he served as Program Director for Operating Systems at
the NSF.  Dr. Scheuermann has served on the editorial board of the
Communications of ACM, The VLDB Journal, IEEE Transactions on Knowledge and
Data Engineering and is currently an associate editor of Data and Knowledge
Engineering and the International Journal of Next-Generation Computing.  Among
his professional activities, he has served as General  chair of the ACM-SIGMOD
Conference in 1988,  General chair of the  ER'2003 Conference and  more
recently as Program Co-Chair of the ACM-SIGPATIAL conference in  2009.  He was
a member of the ACM-SIGMOD advisory board, and prior to this he chaired the
ACM-SIGMOD awards committee His  research interests are in  distributed
database systems, mobile computing, sensor networks and data mining. He has
published more than 120 journal and conference papers. His research has been
funded by NSF, NASA, HP, Northrop Grumman, and BEA, among others. Peter
Scheuermann is a Fellow of IEEE and AAAS (American Association for the
Advancement of Science).